^(125)I-VIP与人胃肠腺癌及癌旁组织细胞膜的体外受体结合特性研究

The characters of ^(125)I-VIP binding to the receptors derived from human gastrointestinal adenocarcinoma and their adjacent tissues

探讨^（１２５）Ｉ－血管活性肠肽（ＶＩＰ）与人胃腺癌及癌旁组织细胞膜、结肠腺癌及癌旁组织细胞膜的体外受体结合特性。^（１２５）Ｉ－ＶＩＰ采用ＣＨ－Ｔ法制备， Ｓｅｐｈａｄｅｘ Ｇ－５０柱层析纯化，硅胶６０Ｆ_（２５４）薄板层析（ＴＬＣ）检测。^（１２５）－Ｉ－ＶＩＰ与人胃肠腺癌及癌旁组织细胞膜进行体外时间－温度结合实验、饱和结合实验和竞争结合实验。结果显示：碘标记率７０％，^（１２５）Ｉ－ＶＩＰ比活度１８ＴＢｑ／ｍｍｏｌ，放射化学纯度９８％；^（１２５）Ｉ－ＶＩＰ与人胃腺癌及癌旁组织细胞膜、结肠腺癌及癌旁组织细胞膜的结合具有温度与时间依赖性、可饱和性及特异性；Ｓｃａｔｃｈａｒｄ作图均为一直线，提示上述组织细胞膜含有单一位点ＶＩＰ受体；胃腺癌细胞膜及癌周组织细胞膜、结肠腺癌细胞膜及癌周组织细胞膜上ＶＩＰ受体的Ｋ_ｄ值分别为１．９１、１．２６、０．９７、１．５３ｎｍｏｌ／Ｌ；Ｂ_（ｍａｘ）分别为３３９、１５６、３０４、 １５１ｆｍｏｌ／ｍｇ。研究结果表明人胃肠腺癌细胞膜与其癌旁组织细胞膜相比， ＶＩＰ受体亲和力无明显变化，最大结合容量明显增加，为ＶＩＰ受体显像奠定了直接的实验依据。

To investigate the characteristics of ^(125)I-VIP binding to human gastrointestinal adenocarcinoma and their adjacent tissue. VIP was labeled with Na^(125)I using chloramine -T method, separated by Sephadex G-50 column chromatography and examined by silica 60F_(254) thin layer chromatography. The effects of time and temperature on the specific binding were examined, saturable binding and competitive binding between ^(125)I-VIP and VIP receptors in membranes from gastrointestinal adenocarcinoma and their adjacent tissue were carried out. The results showed that labeling rate was 70%, the specific activity of ^(125)I-VIP was 18TBq/mmol, the radiochemical purity was better than 98%. A single specific binding sites of high affinity were present in gastric adenocarcinoma and its adjacent tissue as well as in colon adenocarcinoma and its adjacent tissue. The K_d and B_(max) values were 1.19nmol/L and 339fmol/mg protein, 1.26nmol/L and 156fmol/mg protein, 0.97nmol/L and 304fmol/mg protein, 1.53nmol/L and 151fmoll/mg protein respectively. The present study demonstrated that the binding sites of VIP on human gastrointestinal adenocarcinoma were more abundant than their adjacent tissue membrane, which provide valuable experimental evidence for VIP receptor imaging.